EP0952625B1 - Antenna for several radio communications services - Google Patents

Description

The invention relates to an antenna according to the preamble of claim 1 ( US5,402,136 ). One in the DE 195 10 236 A1 described antenna has a capacitive surface 1 and a thereto substantially vertically oriented antenna conductor 4. Together with the conductive base 2 and the there decoupled signals from the coupling conductor 15 thus an antenna is formed monopoly character whose polarization direction is given substantially perpendicular to the roof capacity is. By introducing slots into the roof capacity, this frequency-dependent electrically divided, so that there is an antenna for multiple radio services for the monopoly operation with the roof capacity 1 perpendicular polarization oriented. Antennas of this type thus have the limitation of polarization perpendicular to the roof capacity. The antenna concealable function of communicating with a plurality of vertically polarized mobile terrestrial telephone services and the multi-frequency communication with satellite services, which, whether linearly or circularly polarized, are primarily aimed at horizontal polarization is with an antenna of the prior art Technology not possible.

The object of the invention is therefore to design an antenna according to the preamble of claim 1 such that a better coupling is given to the horizontally polarized field.

This object is achieved in an antenna according to the preamble of claim 1 by the features stated in the characterizing part of this claim.

With an antenna according to the invention the advantage is achieved to cover with a component a whole variety of terrestrial and satellite radio services with correspondingly little effort. Especially for mobile radio services can be compact Vehicle antennas designed, for example, the mobile phone services GSM in the D network (about 0.9 GHz) and E network (about 1.8 GHz) with vertical polarization and at the same time the satellite radio service for the location (GPS radio service at about 1.5 GHz ) with predominantly horizontally and circularly polarized incidental waves due to several zenitnaher satellites. In contrast to the vertically polarized radio service with a zero point of the radiation pattern in the zenith, the GPS navigation service requires a circularly polarized antenna with a maximum of reception in the zenith. This requirement can be met with little effort with an antenna according to the invention in an advantageous manner.

• Fig. 1a: Antenne mit dem Charakter eines Monopols nach der Erfindung mit flächigem, mit der Grundfläche verbundenem Antennenleiter 4, einer Dachkapazität 1 und darin befindlichem geschlossenem Lambda/2-Schlitz 3 mit Resonanz im Frequenzbereich des weiteren Funkdienstes mit zur Ebene der Dachkapazität paralleler Polarisation mit Anschlußpunkten 9a, 9b, mit unsymmetrischer Leitung 10 und Antennenanschlußstelle 13 für den weiteren Funkdienst und mit Ankoppelleiter 15 und Antennenanschlußstelle 14 für den ersten Funkdienst;
• Fig. 1b: Antenne wie in Fig. 1a, jedoch mit rohrförmigem Antennenleiter 4 mit unsymmetrischer Leitung 10 in dessem feldfreien Inneren und mit auf der leitenden Grundfläche 2 befindlicher Frequenzweiche 16, in welche die unsymmetrische Leitung 10 eingeführt ist und an welche der vertikal orientierte Antennenleiter 4 angeschlossen ist und mit getrennten Antennenanschlußstellen (14, 13) am Ausgang der Frequenzweiche;
• Fig.2: Antenne gemäß Fig. 1a, jedoch mit doppelseitig kaschierten Leiterplatten mit zwei offenen, ca. Lambda/4-langen Schlitzen 3 mit unterschiedlichen Längen für zwei weitere Funkdienste bei unterschiedlichen Frequenzen in der die Dachkapazität bildenden leitenden Fläche auf der einen Seite der Leiterplatte mit jeweils einem Anschlußpunkt 9a an eine Streifenleitung auf der anderen Seite der Leiterplatte (grau schattiert), deren Masseleiter durch die leitende Fläche 1 gegeben ist.
• Fig.3a: Antenne gemäß Fig.2, jedoch mit zwei gleichlangen zueinander unter einem Winkel 21 von ca. 90 Grad angeordneten Schlitzen 3 zur Ausbildung einer Funktion mit Zirkularpolarisation der Antenne in einem weiteren Frequenzbereich mit einer 90-Grad Hybridschaltung 17 am Ende der beiden unsymmetrischen Leitungen 10 und mit der Antennenanschlußstelle 13 und mit zwei zusätzlichen Schlitzen 22 zur Gestaltung der unterschiedlichen Resonanzfrequenzen der Monopolantennenfunktion für zwei erste Funkdienste (z.B. D-Netz, E-Netz) mit zur Dachkapazität vertikaler Polarisation;
• Fig.3b: Blockdiagramm einer Antenne wie in Fig.3a mit einem der weiteren Antennenanschlußstelle 13 vorgeschalteten Frequenzbandpaß 23 zum ausschließlichen Durchlaß der Signale für den weiteren Funkdienst (GPS) und einem rauscharmen Verstärker (24). Um das Seitenbandrauschen von Funkgeräten 28 des ersten Funkdienstes (GSM) im Empfangszweig des weiteren Funkdienstes (GPS) zu vermeiden, ist eine Bandsperre 26 an der Antennenanschlußstelle 14 für den Frequenzbereich des ersten Funkdienstes (GSM) vorgeschaltet;
• Fig.4 oben: Antenne gemäß Fig.2, jedoch für zwei erste Funkdienste (z.B. D-Netz, E-Netz) mit zur Dachkapazität vertikaler Polarisation mit zwei zusätzlichen Schlitzen 22 zur Gestaltung der unterschiedlichen Resonanzfrequenzen der Monopolantennenfunktion und zwei Schlitzen 3 für den weiteren Funkdienst (z.B. GPS) unter 90 Grad. Mit Hilfe der Kontourkerben 18 werden die wirksamen Schlitzlängen und die Dachkapazität weitgehend unabhängig voneinander für die verschiedenen Frequenzbereiche abgeglichen. Fig. 4 unten: Flächiger, vertikal orientierter Antennenleiter 4 als Träger der Mikrostreifenleitungen für den weiteren Funkdienst;
• Fig. 5: Vertikales Richtdiagramm einer Antenne nach Fig. 4 im GPS-Frequenzband bei zirkularer Polarisation. Als Bezugsantenne wurde eine IEEE Standard Gain Antenne mit an das GPS-Frequenzband angepaßten geometrischen Abmessungen verwendet.

Embodiments of the subject invention are described below with reference to the drawings. It shows:

• Fig. 1a Antenna having the character of a monopole according to the invention with a flat surface-connected antenna conductor 4, a roofing capacitance 1 and therein closed lambda / 2-slot 3 with resonance in the frequency range of the other service with parallel polarization plane with connection points 9a 9b, with unbalanced line 10 and antenna connection point 13 for the further radio service and with connection conductor 15 and antenna connection point 14 for the first radio service;
• Fig. 1b : Antenna as in Fig. 1a but with a tubular antenna conductor 4 with unbalanced line 10 in its field-free interior and with located on the conductive base 2 crossover 16, in which the unbalanced line 10 is inserted and to which the vertically oriented antenna conductor 4 is connected and with separate antenna terminals (14, 13) at the output of the crossover network;
• Fig.2 : Antenna according to Fig. 1a , but with double-sided printed circuit boards with two open, approximately lambda / 4-long slots 3 with different lengths for two more radio services at different frequencies in the roof capacitance forming conductive surface on one side of the circuit board, each with a connection point 9a to a stripline on the other side of the printed circuit board (gray shaded), whose ground conductor is given by the conductive surface 1.
• 3a : Antenna according to Fig.2 , but with two equal to each other at an angle 21 of about 90 degrees arranged slots 3 to form a function with circular polarization of the antenna in another frequency range with a 90-degree hybrid circuit 17 at the end of the two unbalanced lines 10 and the antenna connection point 13 and with two additional slots 22 for shaping the different resonance frequencies of the monopole antenna function for two first radio services (eg D network, E network) with the roof capacity of vertical polarization;
• 3b : Block diagram of an antenna as in 3a with one of the other antenna connection point 13 upstream frequency bandpass filter 23 for the exclusive transmission of the signals for further service (GPS) and a low-noise amplifier (24). In order to avoid the sideband noise of radios 28 of the first radio service (GSM) in the receiving branch of the further radio service (GPS), a band-stop filter 26 is connected upstream at the antenna connection point 14 for the frequency range of the first radio service (GSM);
• Figure 4 above: Antenna according to Fig.2 but for two first radio services (eg D network, E network) with vertical polarization roof capacity with two additional slots 22 for shaping the different resonance frequencies of the monopole antenna function and two slots 3 for the further radio service (eg GPS) below 90 degrees. With the help of the Kontourkerben 18, the effective slot lengths and the roof capacity are largely independently adjusted for the different frequency ranges. Fig. 4 bottom: planar, vertically oriented antenna conductor 4 as a carrier of the microstrip lines for the other radio service;
• Fig. 5 : Vertical directional diagram of an antenna behind Fig. 4 in the GPS frequency band with circular polarization. The reference antenna used was an IEEE standard gain antenna with geometrical dimensions adapted to the GPS frequency band.

Fig. 1a shows an antenna with the character of a monopoly with a two-dimensional antenna conductor 4, which is conductively connected both to the roof capacitance 1 and with the base. Due to the inductive effect of the antenna conductor 4 and the capacitive effect of the roof capacity, a resonance is formed in the frequency range of a first radio service. Thus, a resonant monopole antenna low height can be formed with polarization perpendicular to the roof capacity. The coupling to this resonant monopole takes place via the coupling conductor 15 to form the first antenna connection point 14. In order to achieve the required antenna function with roof capacity parallel polarization for another service with a monopole with roof capacity, according to the invention in the roof capacity 1 is a closed lambda / 2nd Slot 3 with resonance in the frequency range of the other radio service introduced. Similarly, a slot open at one end can be designed with approximately lambda / 4 length. Appropriately selected terminal points 9a and 9b opposite each other on the edges of the slot at a distance 25 from the closed end of the slot make the desired antenna impedance and the width of the slot the desired bandwidth. With the aid of an unbalanced line 10 connected to the connection points 9a, 9b, which is electrically ineffective with respect to the monopole function of the antenna parallel to the conductive surfaces of the roof capacitance 1 and the antenna conductor 4, the connection between the connection points 9a, 9b with the at the conductive base 2 located further antenna connection point 13 made.

Fig. 1b also shows a monopole antenna as in Fig. 1a but with a tubular antenna conductor 4. The unbalanced line 10 is guided in its field-free interior. The first antenna connection point 14 is formed at the lower end of the antenna conductor 4 with the conductive base 2. To lead out the antenna connection for the other service a crossover 16 is formed in the base, in the interior of the continuation of the unbalanced line 10 is designed as a high impedance in the first frequency range choke and the antenna terminal 13 is designed without affecting the monopole function of the antenna.

In Fig. 2 In an advantageous embodiment of the invention, the roof capacitance 1 and the vertically oriented, flat-shaped antenna conductor 4 are designed as printed circuit boards laminated on both sides. The conductive surfaces are formed by the conductive material located on one side of the circuit boards and are electrically connected at the abutting edge. The unbalanced line is designed as stripline 10, wherein the stripline is printed on the opposite side of the conductive surface 1 and the surface forms the ground conductor of the line 10. The connection between the strip conductor of the strip line 10 and the connection point 9a can be done in a simple manner by plated-through. Of the Terminal point 9b is defined by the perpendicular to the slot direction course of the strip conductor as the point 9a opposite point at the slot edge. To clarify the generality of the inventive concept are in Fig. 2 two slots 3 with different lengths and different polarization directions within the two common polarization planes parallel to the roof capacity with separate unbalanced lines 10 and other antenna terminals 13 shown. As a result, several other radio services with different frequencies for the polarization plane can be detected.

As a further advantageous embodiment of the invention is in Fig. 3a an antenna is shown in which the conductive base is horizontally oriented and the monopole antenna is tuned for the frequency band of a vertical polarization terrestrial telephone service as the first service and tuned as a second service to a satellite service with substantially horizontally polarized incident waves.

Such an antenna is for example particularly suitable for combining the terrestrial GSM telephone service with the GPS satellite radio for use as a vehicle antenna with horizontal conductive base 2. Here, the roof capacity and the vertically oriented antenna conductor 4 are dimensioned such that in the GSM frequency range Resonance exists and the slot 3 is designed in length and width such that its resonance is suitable for the reception of the GPS signals. In addition to the requirement of maximum radiation in the zenith, at the same time to fulfill the condition of the circular polarization, two slots 3, each with two connection points and 9a, 9b, each with a connected unbalanced line 10 for the further radio service GPS with circular polarization available. The slots in the conductive plate of the roof capacity are for this purpose oriented at an angle of almost 90 degrees to each other so that the reception of the circularly polarized waves with a predetermined direction of rotation is optimal. Both slots are exemplified as lambda / 4-resonant slot lines with open ends at the edge of the roof capacity realized. The distance 25 of the connection points 9a, 9b from the closed end of the slot is chosen favorably in view of the characteristic impedance of the line connected thereto. The two lines are connected at their other ends to the two inputs of a 90-degree hybrid circuit, in which one of the two received signals is changed by 90 degrees in phase and after correctly polarized summary of the signals on Output of the hybrid circuit is the appropriate circular polarization direction at the antenna connection point 13.

A particular advantage of the invention is the ease of implementation by using printed circuit boards for the production of the conductive surfaces and the lines. This technique allows a very good reproducibility of the finely tuned structures in the manufacturing process. In this case, the roof capacitance 1 and the vertically oriented, planar-shaped antenna conductor 4 are designed as printed circuit boards laminated on both sides, wherein the conductive material located on one side of the printed circuit boards forms the conductive surface. The unbalanced line 10 is designed as a strip line, wherein the strip conductor is printed on the opposite side of the conductive surface and the conductive surface forms the ground conductor of the line.

An advantage of the invention is the relatively good decoupling between the antenna terminals 13 and 14. Due to the extremely large level differences between the transmitted GSM signals and the GPS signals to be received, it is advantageous to the sensitive GPS receiver from non-linear effects by large Signal level to protect the antenna terminal 13 a bandpass filter 27 for this frequency range downstream. In order to achieve good signal / noise ratios in the GPS range, it is also advantageous to add a low noise preamplifier 24 without lossy leads. In order to avoid the sideband noise of GSM radios 28 in the GPS frequency range, it is recommended that a band-stop filter 26 of the antenna terminal 14 upstream.

In order to design an antenna function for an additional first radio service with a higher frequency and with a polarization oriented vertically to the conductive base, slots 22 can be introduced into the roof capacity 1 in a manner known per se. In Figure 4 Such an antenna for the two terrestrial mobile telephone services (D and E network) is shown. With the help of the notches 18, the slot lengths and the roof capacity for the design of the various resonance frequencies can be determined largely separately from each other.

With the in Fig. 4 In addition to the radio services of the D and E network, the satellite navigation service GPS can also be received via a further connection point 13.

In contrast to the vertically polarized, first radio service with a zero point of the directional diagram at zenith, the GPS navigation service requires a circularly polarized antenna with a maximum of reception at zenith. Therefore, two further slots, which are arranged at an angle of 90 ° to each other, are introduced into the conductive surface of the roof capacitance 1 and operated as λ / 4-slot antennas. The effective for the edge current of the D-network input impedance of the slots is sufficiently low-impedance, since the slots have a strong resonance at 1575 GHz, so that the radio antenna in the D-network is not affected.

The decoupling points of the two GPS slot antennas are combined as close as possible and chosen so that their impedance is 50 ohms. The RF signals of the GPS antennas are guided with coaxial lines by utilizing the conductive surface of the roof capacitance 1 as a ground conductor via the antenna conductor 4 to a 90 ° hybrid.

If one uses for the conductive surface of the roof capacity 1 double-laminated, 1mm thick board material (eg FR4) for the antenna Fig. 4 , so on the top of all slots from the applied copper layer can be etched. The two required RF lines for GPS are realized as microstrip lines, with the underside of the board carrying the strip conductors. Via the antenna conductor 4, the GPS signals are also continued as microstrip lines and connected to the also executed in stripline technology 90 ° hybrid on the base plate. This creates an easy-to-set-up and easily reproducible antenna.

Fig. 5 shows a measured vertical section of the radiation pattern of the antenna Fig. 4 in the upper hemisphere in circular polarization. The fact that the GPS slot antennas after Fig. 4 In a non-symmetrical environment, there are still diagrams for other azimuth angles in the elevation range of 60 ° to 90 °. Otherwise, the performance of a ceramic patch antenna is achieved.

The transmission and reception characteristics of the antenna Fig. 4 In the D and E radio service are influenced by the additional GPS slot antennas only little.

The total height 20 of the antenna after Fig. 4 is only about 20 mm and can be built on a circular base plate with a diameter of less than 9 cm.

List of terms

• Roof capacity (1)
• conductive base (2)
• Slot (3)
• Antenna conductor (4)
• first edge (5)
• second edge (6)
• Slit length (7)
• Slit width (8)
• first connection point (9a)
• second connection point (9b)
• unbalanced line (10)
• Inner conductor (11)
• Ground conductor (12)
• further antenna connection point (13)
• first antenna connection point (14)
• Connection ladder (15)
• Crossover (16)
• 90-degree hybrid circuit (17)
• Contour notches (18)
• Connection point of the first service to roof capacity (19)
• Distance of the roof capacity 1 to the conductive ground plane 2 (20)
• Angle (21)
• additional slots (22)
• Frequency bandpass (23)
• low-noise amplifier (24)
• Distance (25)
• Band-stop filter (26)
• Bandpass (27)
• Radio (28)

Claims (9)

1. Antenna for multiple radio services with the character of a monopole above a conductive base (2), with an antenna conductor (4) and at least one top-loading capacitor (1) arranged planar and oriented substantially perpendicular to the antenna conductor (4) for a first radio service with a polarization oriented perpendicular to the top-loading capacitor (1), wherein a first connection point (19) of the first radio service is formed at the top-loading capacitor, and an antenna function for at least a further radio service with a polarization oriented parallel to the top-loading capacitor (1), wherein the top-loading capacitor is implemented in the form of a conductive plate or a thin conductive layer, wherein at least one slot (3) is inserted into the conductive plate or layer for configuration of the antenna function for the at least further radio service, whose slot length (7) for forming a resonance in the frequency range of the further radio service and whose slot width (8) for forming a suitable impedance bandwidth are suitably selected,
   characterized in that
   for decoupling of signals in the further radio service, a first and second connection point (9a, 9b) are formed at the edges of the slot (3) at opposite points, and an unbalanced electrical line (10) is connected with its inner conductor (11) to the first connection point (9a) and with its ground conductor (12) to the second connecting point (9b) and is lead without electrically effective distance in parallel to the conductive plate forming the top-loading capacitor (1) and also in parallel to the surface of the vertically oriented antenna conductor (4) and establishes a connection to an antenna connection location (13) for the further radio service.
2. The antenna according to claim 1,
   characterized in that
   the antenna conductor (4) is arranged planar conductive and conductively connected via a first edge (5) to the top-loading capacitor (1) and conductively connected via a second edge (6) to the conductive base (2) and the antenna connection location (13) for the further radio service is provided on the conductive base (2).
3. The antenna according to claim 1 or 2,
   characterized in that
   the top-loading capacitor (1) and the vertically oriented, planar formed antenna conductor (4) are arranged as clad printed circuit boards, conductive on both sides, and a conductive surface is formed by the conductive material on a respective side of the printed circuit board and the unbalanced line (10) is implemented as strip line, wherein said strip line is printed on the opposite side of the conductive surface and the conductive surface forms the ground conductor of the line (10).
4. The antenna according to any of the claims 1 to 3,
   characterized in that
   the conductive base (2) is oriented horizontally, and the monopole antenna is tuned for the frequency band of a terrestrial telephone radio service with vertical polarization as a first radio service and is tuned to a satellite radio service, as further radio service, with substantially horizontally polarized incident waves.
5. The antenna according to claim 1 to 4,
   characterized in that
   the top-loading capacitor (1) and the antenna conductor (4) perpendicular oriented thereto are dimensioned such that resonance is provided in the first radio service in the GSM frequency range, and the slot (3) is formed in length and width such that its resonance is suitable for the reception of the further radio service in the GPS frequency range.
6. The antenna according to any of the claims 1 to 5,
   characterized in that
   two slots (3) are provided for a further radio service with circular polarization each having two connection points (9a, 9b) and each with an unbalanced line (10) connected thereto, and the two lines (10) are lead to two inputs of a 90-degree hybrid circuit (17), at which output the antenna connection location (13) is formed for the further radio service, and the slots (3) are oriented in the conductive plate of the top-loading capacitor (1) at an angle of nearly 90 degrees to each other such that the reception of circularly polarized waves at predetermined rotation is optimal.
7. The antenna according to claim 5,
   characterized in that
   at the antenna connection location (13) for the further radio service, a frequency band-pass (23) for passage of the signals for the further radio service and a low noise amplifier (24) on one of the conductive surfaces of the antenna, preferably on the conductive base (2) of the antenna, are provided.
8. The antenna according to any of the claims 3 to 7,
   characterized in that
   slots (22) are inserted into the top-loading capacitor (1) in a known manner for configuration of an antenna function for a second first radio service with higher frequency and with a polarization oriented vertically to the conductive base (2).
9. The antenna according to any of the claims 1 to 7,
   characterized in that
   the antenna conductor (4) is formed as three-dimensional body, and the unbalanced line (10) is lead either in the field-free interior of said antenna conductor or electrically ineffective in parallel to the outer surface of said antenna conductor (4) to the conductive base (2) and a diplexer (16) is provided on the conductive base (2), into which the unbalanced line (10) is inserted and to which the vertically oriented antenna conductor (4) is connected and on which either separate antenna connection locations (14, 13) for all radio services are present or one common antenna connection location for all radio services is present.

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